Battery, square battery and electric equipment

The utility model relates to the technical field of batteries, in particular to a battery, a square battery and electric equipment. The battery comprises a laminated core, a cover plate and a connecting piece, the laminated core comprises pole pieces and diaphragms, the pole pieces and the diaphragms are mutually laminated and form an empty foil part embedded into the laminated core, the cover plate is located at the top end of the laminated core, the cover plate is provided with a pole column, one end of the connecting piece is welded with the pole column, and the other end of the connecting piece extends into the laminated core. The side face of the other end of the connecting piece is welded to the empty foil part. And the other end of the connecting sheet extends into the laminated core to be welded with the empty foil part, so that the structure between the laminated core and the cover plate is more compact, the space utilization rate between the laminated core and the cover plate is improved, and the vo